In its second such agreement this week, Microsoft has struck a deal under which it will extend amnesty to a company that's using what the software maker claims is patented Microsoft intellectual property embedded in the open source Linux computer operating system. Under a deal with LG Electronics, disclosed late Wednesday, Microsoft will forgo any Linux-related patent claims against the South Korean electronics manufacturer. In return, Microsoft will gain access to certain intellectual property produced by LG.

Can this be understood as MS preparing the legal grounds for a big assault against the FOSS?

it seems that MS is creating a portfolio of FOSS users who have deals with them about the authorized use of their patented software. I assume that these FOSS users, after accepting these deals, are acknowledging that the FOSS that they are using implies the use of the MS intellectual property. I guess that these users don't have the resources (or are just to scary of the 1000 lawyers arriving to their doors) to verify the MS's claims and they just prefer to sign an agreement to avoid any future confrontation.

A portfolio of key users signing these deals gives to MS the "moral/legal" veracity of their infringement claims. They could use this in a variety of scenarios as suing any FOSS developer that uses the so claimed MS property. For example, If User A acknowledges that the FOSS product Z has MS property, then MS could have a legal ground for suing the developer of Z.

I'd like to avoid being pessimistic, but this is scary and shows the worst of the worst faces of MS to deal with competition.

I think Microsoft wants you to be scared. But I suspect Microsoft is scared.

They used to just ignore all GNU and Linux and BSD as worthless bother. Now they know for sure there is a very real threat. They see the handwriting on the wall. They are slashing and punching like a dying man. Maybe.